SOLVED Multiple issues in motion system

Discussion in 'Build Help' started by Stian Indal Haugseth, Jun 5, 2016.

  1. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

    Joined:
    Sep 11, 2015
    Messages:
    573
    Likes Received:
    95
    Hi,

    I was hoping I was ready to start printing now. But doing some test prints now I notice a few issues I do not like.

    1. First think I noticed was this strange knocking/clicking sound. I found It comes from the Z motors / shafts. It looks like I got a lot of Z motion printing a single layer. I feel they almost shudder when they click back and forward adjusting Z. Then I think about I have not seen any actual leveling of the bed in the build manual anywhere. I do not think about the mesh level that I did but adjusting the screws in each corner.

    2. Lumpy feel on the Y axis when I move it manually. It was super smooth before tightening everything.

    3. Over extruding! Using 0.8mm nozzle on E0. I downloaded @Alex9779 fw from https://jenkins.alitecs.de/job/BigBox_Dual-RC/.
      Should I not have two E step configuraions? From M503 I have E304 at the moment.
     
  2. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    1. The motion is from the mesh leveling. Yeah they tick a big, I have that too.
    2. hmm no idea, mine feel also not as before fitting the belts and tightening but isn't it the motor you feel?
    3. There is only one E step config. Marlin does not support different E values for the two hotends. You have to do that in a tool change script if you really need different values. Did you calibrate your filament?
     
  3. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

    Joined:
    Sep 11, 2015
    Messages:
    573
    Likes Received:
    95
    Thanks,

    Still strange noise. have the same ticking after a thorough manual bed level + mesh level.

    By lumpy feel I mean when I move it reasonable slow I can feel slightly tugging. Not just the motor resistance. It might not be an issue but I'm tempted to do a new commissioning as I just got some lithium grease now. Might be worth packing the bearings inside.

    I measured the extrusion and printing 102,8 mm when it should print 100 so it's not that far off. I think my problems are related to printing with a 0.8mm nozzle. Maybe I should switch to the other extruder where I put on a 0.4 nozzle.
     
  4. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    Ya it is from the machine using mesh leveling to level the inconsistencies of the bed... The machine calculated a mash and for each X,Y position it has correction values so the bed moves constantly up and down to even out those inconsistencies...
    This will always happen with both leveling methods (auto and mesh), beside auto just calculates a sloped plane while mesh calculates a different way with a higher resolution.
    The only way you won't get that moving is you have a perfect flat and perfectly adjusted bed to the nozzle... You could simulate, I haven't tried my self but in theory if you enter the same values on every point when leveling the bed there should be no movement because then the firmware thinks you have all perfect...
     
  5. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

    Joined:
    Sep 11, 2015
    Messages:
    573
    Likes Received:
    95
    Yes, but I have been convinces by you that MBL is the way to go. The sag in the x rods is noticeable. Without this sag I would prefer ABL.

    But I don't understand the abruptness of the z motion (the jerkiness). I thought it would be smooth as the bed level doesn't really change that fast.
     
  6. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    Hmmm no idea if it is fast or not, I was worried too at first, I had that sounds and no indication where they came from. Sometime the motion is so low that you have to touch the Z couplers to notice that they are turning... And I think those very few steps the motors are moving are the reason for those sounds.
    So far I know no setting to configure the speed because the speed is depending on the speed of the head, the faster he moves the faster the bed has to be leveled... No idea how to change this or how to phrase an issue...
    But nevertheless I have no issues apart from the feeling that it is not ok because of the sound. The prints do not show any issues from this...
     
  7. Old_Tafr

    Old_Tafr Well-Known Member

    Joined:
    Mar 7, 2016
    Messages:
    560
    Likes Received:
    75
    I'm interested in what the sag is, how did you go about measuring it?
     
  8. mike01hu

    mike01hu Well-Known Member

    Joined:
    Apr 22, 2014
    Messages:
    957
    Likes Received:
    166
    I could not measure any other than flexure due to loose rod clamps that appeared a week or so after using it. Someone else also warned about checking these screws and others after a period of use.
     
  9. Chase.Wichert

    Chase.Wichert Well-Known Member

    Joined:
    Mar 1, 2016
    Messages:
    774
    Likes Received:
    207
    Have you put grease on the z axis rods and acme rods? WIthout grease on the acme rods it will make a lot of noise and stick.
     
    Old_Tafr likes this.
  10. Old_Tafr

    Old_Tafr Well-Known Member

    Joined:
    Mar 7, 2016
    Messages:
    560
    Likes Received:
    75
    Smear grease all down the acme threaded rods and on the smooth rods and run the bed all the way down (then smear on the rods etc. above the bed, and then up and down a few more times........... just beware that the original firmware seems to reset the Z coordinates to zero sometimes so you may find the bed at the bottom and won't move up as it thinks it is at zero. Telling it to home fixed this for me and it ran all the way up again.
     
  11. elmoret

    elmoret Administrator

    Joined:
    Mar 1, 2014
    Messages:
    586
    Likes Received:
    91
    No need to measure really, simple beam calcs:

    With a 500 gram x-carriage sitting atop two 8mm solid steel rods, you're looking at about 30 microns of deflection. With 10mm rods, about 15 microns of deflection.

    But this deflection is constant, and I doubt your bed is within 30 microns of flat anyway.
     
    mike01hu likes this.
  12. R Design

    R Design Well-Known Member

    Joined:
    Oct 7, 2015
    Messages:
    918
    Likes Received:
    183

    What the nozzle experiences relative to the bed works out as being rather more than that because the Y rods are 8mm and bending as well.

    Although they are shorter they have even more weight to bear.

    I keep wondering about replacing the Y rods with 10mm (since the added mass makes no difference there).

    And frequently wonder about swapping X and Y axes (like the BCN sigma) so that the Y axis (which can be fatter and more rigid) is the longer (300mm) one of the two.

    @Stian Indal Haugseth When things are stiff or clicking there are two things that come to mind: alignment and bearings. The commissioning process is very much about keeping everything loose and then tightening slowly in such a way that everything is properly aligned when it becomes rigid at the end. With the default bearings there are always going to be doubts and they can turn bad quite abruptly.
     
  13. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

    Joined:
    Sep 11, 2015
    Messages:
    573
    Likes Received:
    95
    Of course it might be the glass or a combination. But I don't think it's a coincidence the paper I out under the nozzles stick when the x carriage is centered and loose when I move it to the corners. This is me pushing the carriage around so there is no mesh adjustment here.

    All greased up. Moly on the threaded rods and some lithium soap stuff (finally found the stuff in a store) on the smooth rods. should probably take out the bearings to pack them on the inside but I'll wait until I get two Titans and print your dual carriage :)
     
  14. Tom De Bie

    Tom De Bie Well-Known Member

    Joined:
    May 7, 2016
    Messages:
    191
    Likes Received:
    33
    I had the same idea :)
    Already altered the Y-axis brackets...
     

    Attached Files:

  15. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

    Joined:
    Sep 11, 2015
    Messages:
    573
    Likes Received:
    95
    Oh no... Need new rods and bearings! :D
     
  16. Tom De Bie

    Tom De Bie Well-Known Member

    Joined:
    May 7, 2016
    Messages:
    191
    Likes Received:
    33
    already have them lying around ;)
     
  17. mike01hu

    mike01hu Well-Known Member

    Joined:
    Apr 22, 2014
    Messages:
    957
    Likes Received:
    166
    The rods are more than adequate provided you effectively tighten the clamps and fixing screws. I measure less than 20microns across the range of X and Y travel. As I said elsewhere, check screw tightness after a few hours printing and regularly after that. Do not overdo the tightening as you can snap the clamps.
     
    Stian Indal Haugseth likes this.

Share This Page